re F12PWM specs

packaging says fan is 400-1500rpm
website says fan is 300-1350rpm

1: which is the truth ?

2: does chaining 2/3/4 fans together have any affect on fan speed overall ? compared to spec ?

3: do they behave differently when connected to a pwm or on a 4 pin fan header on a motherboard that uses volt modification rather than pwm to control fan speed ?